1 files changed, 15 insertions, 0 deletions

diff --git a/async/src/async_impl.h b/async/src/async_impl.h
index 58f6ced..eccbc9b 100644
--- a/async/src/async_impl.h
+++ b/async/src/async_impl.h
@@ -19,6 +19,7 @@
 #define ASYNC_IMPL_H
 
 #include "async.h"
+#include <type_traits>
 
 namespace Async {
 
@@ -45,6 +46,20 @@ struct prevOut {
     using type = typename std::tuple_element<0, std::tuple<T ..., void>>::type;
 };
 
+template<typename T>
+inline typename std::enable_if<!std::is_void<T>::value, void>::type
+copyFutureValue(const Async::Future<T> &in, Async::Future<T> &out)
+{
+    out.setValue(in.value());
+}
+
+template<typename T>
+inline typename std::enable_if<std::is_void<T>::value, void>::type
+copyFutureValue(const Async::Future<T> &in, Async::Future<T> &out)
+{
+    // noop
+}
+
 } // namespace Detail
 
 } // namespace Async